This invention relates to an apparatus for the production of tubular sheaths for tubular electrodes with differing geometrical cross-sections. Such tubular sheaths can be of many different types and be produced in different ways. Particularly, the invention relates to such tubular sheaths as are formed on a mandrel.
It is heretofore known to form tubular sheaths for tubular electrodes for electrical storage batteries on mandrels by different processes and starting from different sheath material. For example, see disclosures in commonly assigned U.S. Pat. Nos. 2,896,006; 3,725,130; and 3,801,399. These operations have been carried out both by continuous methods and by discontinuous methods.
Discontinuous methods are applied for example with a preliminary stiffening of the tubular sheath, the latter consisting of a mat of woven-together tube and thermoplastic, or mainly thermoplastic fibres. The procedure adopted in such cases is to cut or punch pieces of the tubular mat having a length somewhat exceeding the desired length of the final product. In each tubular channel of the mat there is inserted a mandrel, and the mat is subjected to the desired treatment which may be a heat treatment or an impregnation or a combination of these. After this, the mandrels are withdrawn and the mat is cut to the desired length.
In the case of continuous tube production, the tubular sheath material is fed in the form of an endless belt over a mandrel which in some way is held still. In one known arrangement, disclosed for example in the above-mentioned U.S. Pat. No. 2,896,006 and depicted therein in FIG. 5, the holding of a mandrel M can be effected for example by the mandrel being designed with a bend B at the end where the feeding-on of the sheath material S takes place, with such bend being arranged to hold the mandrel in place over a disc or roller R. Attention is directed to commonly assigned U.S. Pat No. 3,725,130 for an example of such an arrangement. The holding-still of the mandrel can also be effected by the mandrel at its feed-in end having a narrower section, and wherein it is held in place by rollers or wheels going transversely across the mandrel and disposed in pairs with a gap therebetween which is less than the largest diameter of the mandrel but greater than the smallest diameter of the mandrel.
All of the methods described above involve certain disadvantages. As regards the discontinuous methods, it is obvious that these methods are, on the one hand, demanding in respect of labor required, and on the other hand give rise to an unnecessary waste of material. Concerning the continuous methods described above, there occurs to some extent an undesirable action on the sheath material resulting from the arrangement for holding the mandrel in position; and as a result of this, furthermore, such methods involve unnecessary technical complications for feeding and treating the sheath material.
It is, therefore, an object of the present invention to provide novel apparatus for treating mandrel-mounted sheath material which avoids undesirable action upon the sheath by the mandrel-supporting mechanism.
It is another object to provide such novel apparatus for treating sheaths of different cross-sectional configurations.
It is a further object of the invention to provide such apparatus which minimizes relative displacement of braided threads in the sheath.
It is yet another object of the invention to provide such novel apparatus wherein the sheath-supporting mandrel is suspendingly supported in a manner having minimal disruptive effects on the sheath.